Robert Pattinson's sisters have reportedly told their brother to steer clear of cheating Kristen Stewart.

The British actor was left heartbroken earlier this year when the Twilight actress admitted to having an affair with married film director Rupert Sanders.

Pattinson has reportedly been struggling to deal with the pain of Stewart's betrayal, but his protective sisters have reportedly told him he's better off without the star.

"Robert's sisters were fuming with Kristen for hurting their brother in the way she did. Lizzy and Victoria feel terrible for heartbroken Robert, especially because of the embarrassment that was caused by the manner in which the affair was exposed. They've told him that there's no way he can take Kristen back after what she did to him," a source told Radar Online.

"It's a case of once she's cheated, what's to stop her doing it again and Lizzy and Victoria are pretty unforgiving over Kristen's actions. Instead, they believe Robert should embrace singledom, throw himself into work and not consider settling down with anyone until he's ready.

"They will kill him if he gets back with Kristen."

Stewart's affair with Pattinson was exposed by a series of photos, which showed them in a number of amorous clinches.